Chapman Pincher was ballyhooed by his own newspaper, The London Daily Express, as the world’s greatest reporter, and he introduced himself as such. He insinuated himself into the murky world of spy chiefs, generals, politicians and royalty by taking them to lunch at a fine French restaurant, say, or joining them for pheasant hunting and salmon fishing.

His reward was 40 years of scoops about double agents, secret weapons and the inner workings of governments. In 1966, not bothering to wait four more years, his paper called him its reporter of the decade. His best tributes came perhaps from his enemies.

“Can nothing be done to suppress or get rid of Pincher?” Prime Minister Harold Macmillan wrote to his defense minister in 1959.

Pincher said he wondered exactly what “get rid of” meant — particularly in the netherworld of spies that he prowled. But there could be no doubt what the British historian E.P. Thompson meant when he wrote about Pincher in The New Statesman in 1978. Thompson, using the names of the British domestic and international spy agencies, likened Pincher to “a kind of official urinal where high officials of MI5 and MI6 stand side by side patiently leaking” — presumably secrets.

Pincher, who died at 100 on Tuesday at his home in Kintbury, England, considered Thompson’s insult his greatest professional compliment.

In announcing his death, his son, Michael, recalled the message that Pincher had asked to be conveyed: “Tell them no more scoops.”

In one of his many scoops, he learned precious details about the atomic bomb before any American newspaper did after the United States dropped one on Hiroshima in 1945. He documented the treachery of the theoretical physicist Klaus Fuchs, who gave Moscow information about the hydrogen bomb he had helped develop. He broke news about the Cambridge Five, the British intelligence officers who spied for Russia in the 1940s and ’50s.

In 1961, Pincher detailed how George Blake, an MI6 operative, had betrayed 40 or so agents to the Soviets. In 1964, he scooped other English newspapers and Pravda, the official Soviet paper, on the exchange of Greville Wynne, a British businessman jailed as a spy in Russia, for the Soviet spy who called himself Gordon Lonsdale.

In 1967, he reported that British intelligence was reading the cables and telegrams of private citizens. His revelation in 1971 that chauffeurs, gardeners and others working at the Soviet Embassy in London were actually spies resulted in the expulsion of more than 100 of them from Britain.

Of his more than 30 books, his most influential was “Their Trade Is Treachery” (1981), in which he made the case that Roger Hollis, a former director general of MI5, was a Soviet spy. Several investigations, including one commissioned by Prime Minister Margaret Thatcher, could not find enough evidence to make the accusation stick.

Pincher did it all his own way. He said he never took notes, so as not to interrupt the flow of conversation. He had an unimpeachable memory, he said. He tried never to see or touch a classified document, relying instead on the summaries of people he trusted.

If sources wanted him to delay printing an article, he usually agreed — knowing he would be first in line if they changed their minds. He more than once wrote a phony story at the behest of the British government.

In its obituary Wednesday, The Guardian reported that in the 1950s the government was worried that Japanese protesters would try to disrupt a planned nuclear test on Christmas Island by showing up in 1,000 boats. Pincher printed the lie that the test was being postponed. It went ahead with no hitches.

“Few endeavors,” The Guardian quoted him as saying, “gave me more delight.”

Lord Mountbatten, the naval leader and last viceroy of India, once dictated an article to Pincher in the back of his Land Rover while on a grouse shoot, according to The Independent. The article appeared under Pincher’s byline.

Once, when asked if he felt used, Pincher answered: “Absolutely! But my motto was, if the story is new, and particularly if it’s exclusive, I’m open for use any day.”

Henry Chapman Pincher was born on March 29, 1914, in a field hospital tent in Ambala, India, where his father was a major in the British Army. After the family returned to England, his father ran a sweet shop and later a pub.

Henry, known as Harry, graduated from King’s College London with a degree in botany and zoology. He taught science at a high school in Liverpool and wrote articles for farm publications.

Drafted into the British Army, he was assigned to a division working on new rocket weapons. Through a chance meeting with an old acquaintance who worked for The Daily Express, he began feeding information on these projects to the newspaper. He made friends with a leading defense scientist, who introduced him to other scientists and military leaders in what Pincher called “the charmed circle.”

Offered a job at The Express, he quickly advanced to the position of defense, science and medical editor. He wrote in a memoir, “Chapman Pincher: Dangerous to Know,” published in February, that an Express editor chose his middle and last names for his byline because he thought it sounded “pompous.”

That may have helped cement his chummy relationships with sources far richer and more aristocratic than he — although by his lights it was his hunting pheasant with them across autumn fields, shotguns at the ready, that did the trick. When pursuing game, he told The Guardian, “your guard’s all gone, you’re pals, having a difficult day with the birds or a good one.”

Pincher is survived by his wife, Constance Sylvia Wolstenholme, who is known as Billee; a daughter, Patricia Chapman Pincher, and a son, Michael, both from a previous marriage; three stepchildren and a number of grandchildren and great-grandchildren.

Pincher liked to recall the days when he would retreat to a corner of his favorite London restaurant with a source and collect sometimes momentous information over a bottle of good wine.

“I’m just thinking of coming out of L’Ecu after a nice lunch, walking back to Fleet Street in the sunshine and feeling great, knowing that I’d got two bloody scoops that nobody could touch and they were bound to lead the paper,” he told The Guardian. “Oh, it was wonderful, quite wonderful.”